Conventionally, swimming is adopted in fitness facilities or the like as one of the programs for enhancing physical strength. Swimming is utilized also for medical treatment. In water, a large load is not exerted on a patient's knee joints and the like, because part of his or her weight is borne by buoyancy. Therefore, swimming is suitable for kinesitherapy for diabetics or the like who suffer from arthralgia.
In such kinesitherapy, it is generally difficult to judge, from the facial expression or the body motion of the patient, whether the exercise being performed by the patient is exerting a proper load on the patient. Therefore, the degree of a load by the exercise is often checked by measuring the pulse rate of the patient, for example.
Conventionally, various pulse measuring apparatuses are developed. However, such apparatuses are not satisfactorily waterproof for use at a poolside, or even when satisfactorily waterproof, they are not suitable for use in water. For example, usually, the use of a pulsimeter having a watch function in water is not allowed.